PPAR and liver injury in HIV-infected patients

Liver Disease in Human Immunodeficiency Virus Infection

Liver disease in human immunodeficiency virus (HIV) remains a main cause of morbidity and mortality. Liver-related morbidity and mortality can be caused by multiple etiologic factors, including opportunistic infections, direct and indirect effects of antiretrovirals, direct and indirect effects of HIV, and viral hepatitides. These factors present with varied liver pathophysiologic mechanisms that lead to abnormalities in liver enzymes and synthetic function test, followed by distinct clinical presentations. This article elucidates the direct effects on HIV in the liver and explores the diagnostic and management challenges in patients with HIV in the era of highly active antiretroviral treatment.

Liver involvement in human immunodeficiency virus infection

The advances in management of patients with acquired immunodeficiency syndrome (AIDS) with highly effective anti-retroviral therapy (HAART) have resulted in increased longevity of patients with human immunodeficiency virus (HIV) infection. AIDS-related illnesses now account for less than 50 % of the deaths, and liver diseases have emerged as the leading cause of death in patients with HIV infection. Chronic viral hepatitis, drug-related hepatotoxicity, non-alcoholic fatty liver disease, and opportunistic infections are the common liver diseases that are seen in HIV-infected individuals. Because of the shared routes of transmission, co-infections with hepatitis B virus (HBV) and hepatitis C virus (HCV) are very common in HIV-infected persons. Hepatitis C is the most common viral hepatitis seen in HIV-infected patients. With the availability of directly acting agents, treatment outcome of HCV is comparable to that seen in non HIV-infected patients. Careful monitoring is required for drug interactions and drug-induced hepatotoxicity and modification of drugs should be done where necessary. The results of liver transplantation in select HIV-infected patients can be comparable with those of HIV-negative patients.

Do the epidemiology, physiological mechanisms and characteristics of hepatocellular carcinoma in HIV-infected patients justify specific screening policies?

Reducing the incidence of hepatocellular carcinoma (HCC) in HIV-infected patients has become a serious problem when managing these patients. There are many explanations for this disease evolution, which notably include their longer survival under effective antiviral therapy and also the more rapid evolution of chronic liver disease. Despite recent advances in the management of hepatitis B (HBV) and hepatitis C (HCV) viral diseases, which will probably increase the number of patients achieving a virological response, HIV-infected patients with cirrhosis are still at risk of the onset of HCC. This evolution to HCC is also correlated to other comorbidities such as excessive alcohol consumption and nonalcoholic steatohepatitis (NASH). HCC thus remains a public health issue in this population. The poor prognosis and aggressiveness of HCC have been fully demonstrated, but the mechanisms underlying this aggressiveness are not yet well defined. As well as underlying mechanisms that contribute to accelerating hepatocarcinogenesis in HIV-infected patients, there are other reasons why HIV-infected patients should be considered a higher risk population. This review discusses the principal epidemiological determinants; the mechanisms of pathogenesis; and the treatment of HCC in HIV/HBV and HIV/HCV coinfected patients. It also discusses the probable need to develop a specific screening policy for HCC in this population in order to prevent the rapid development and to make them more amenable to a curative treatment.

HIV-1 Vpr enhances PPARβ/δ-mediated transcription, increases PDK4 expression, and reduces PDC activity

HIV infection and its therapy are associated with disorders of lipid metabolism and bioenergetics. Previous work has suggested that viral protein R (Vpr) may contribute to the development of lipodystrophy and insulin resistance observed in HIV-1-infected patients. In adipocytes, Vpr suppresses mRNA expression of peroxisomal proliferator-activating receptor-γ (PPARγ)-responsive genes and inhibits differentiation. We investigated whether Vpr might interact with PPARβ/δ and influence its transcriptional activity. In the presence of PPARβ/δ, Vpr induced a 3.3-fold increase in PPAR response element-driven transcriptional activity, a 1.9-fold increase in pyruvate dehydrogenase kinase 4 (PDK4) protein expression, and a 1.6-fold increase in the phosphorylated pyruvate dehydrogenase subunit E1α leading to a 47% decrease in the activity of the pyruvate dehydrogenase complex in HepG2 cells. PPARβ/δ knockdown attenuated Vpr-induced enhancement of endogenous PPARβ/δ-responsive PDK4 mRNA expression. Vpr induced a 1.3-fold increase in mRNA expression of both carnitine palmitoyltransferase I (CPT1) and acetyl-coenzyme A acyltransferase 2 (ACAA2) and doubled the activity of β-hydroxylacyl coenzyme A dehydrogenase (HADH). Vpr physically interacted with the ligand-binding domain of PPARβ/δ in vitro and in vivo. Consistent with a role in energy expenditure, Vpr increased state-3 respiration in isolated mitochondria (1.16-fold) and basal oxygen consumption rate in intact HepG2 cells (1.2-fold) in an etomoxir-sensitive manner, indicating that the oxygen consumption rate increase is β-oxidation-dependent. The effects of Vpr on PPAR response element activation, pyruvate dehydrogenase complex activity, and β-oxidation were reversed by specific PPARβ/δ antagonists. These results support the hypothesis that Vpr contributes to impaired energy metabolism and increased energy expenditure in HIV patients.

A pilot study of telmisartan for visceral adiposity in HIV infection: the metabolic abnormalities, telmisartan, and HIV infection (MATH) trial

Background

Visceral adiposity in the setting of HIV infection and antiretroviral therapy (ART) is not fully understood, and treatment options remain limited. Telmisartan, an angiotensin receptor blocker and partial PPAR-γ agonist, has been shown to decrease visceral fat and improve metabolic and inflammatory parameters in HIV-uninfected subjects.

Methods

HIV-infected subjects with HIV-1 RNA <50 copies/mL on ART and (women/men) waist circumference >94/95 cm or waist: hip ratio >0.88/0.94 received open-label telmisartan 40 mg po daily for 24 weeks. Adipose tissue (AT) volumes were quantified by L4–L5 single slice computed tomography. Metabolic and inflammatory markers were obtained fasting. Thirty-five subjects provided 80% power to detect a 10% 24-week decrease in visceral AT (VAT, two-sided α = 0.05).

Results

Thirty-five subjects enrolled and completed the protocol. At entry (median or %): age 49 years, 43% female, 77% non-white, 91% non-smokers, CD4+ T cell count 590 cells/mm³, BMI 31 kg/m². AT responses were heterogeneous, with statistically significant losses of median (IQR) total (TAT, 2.9% (−9.8, 0.7), p = 0.03) and subcutaneous (SAT, −2.7% (−9.8, 1.1), p = 0.03) AT, but not VAT (−2.7% (−20.5, 14.2), p = 0.53). Significant decreases in waist circumference and waist:hip ratio occurred (both p<0.001) without BMI or weight changes. In an exploratory analysis, significant increases in TNF-α occurred among female subjects without changes in other inflammatory or metabolic markers. No related adverse events occurred.

Conclusions

Telmisartan was well tolerated. Small losses of AT from all depots were observed after 24 weeks of telmisartan therapy. Further study is needed to determine whether HIV-infected patients can receive metabolic benefits from telmisartan.

Trial Registration

ClinicalTrials.gov NCT01088295

Fatty liver and anti-oxidant enzyme activities along with peroxisome proliferator-activated receptors γ and α expressions in the liver of Wilson's disease

BACKGROUND

The mechanisms of liver damage and steatosis in Wilson's disease (WD) presenting accumulation of copper generating oxidants remain unclear. Recent studies have shown that peroxisome proliferator-activated receptors (PPARs), in particular PPARs α and γ, regulate fat content of the liver together with the anti-oxidant and anti-inflammation systems. However, such PPARs have never been studied in WD.

METHODS

We examined PPARs along with the liver damage and steatosis of WD using liver specimens from affected patients exhibiting mild liver damage (group I, n = 5), moderate or greater liver damage (group II, n = 10) and fulminant hepatic failure (group III, n = 5), and from asymptomatic carriers (group H, n = 4).

RESULTS

PPAR α expression was increased over the control levels in groups H and I but was decreased in groups II and III in parallel with the progression of liver damage (group H = I>II>III). PPAR γ expression was inversely increased (group H<I<II<III). Mn-dependent superoxide dismutase (Mn-SOD), CuZn-SOD, and catalase activities were decreased in the affected three groups, and were increased in group H. Among group II exhibiting substantial inter-individual variances in parameters, the severity of steatosis showed a significant positive correlation with PPAR γ expression (p<0.001) but not PPAR α expression. CuZn-SOD activity was positively correlated with PPARα expression (p<0.05) but not PPAR γ expression.

CONCLUSION

These results suggest that changes of PPARs γ and α are associated with the steatosis and the impairment of anti-oxidant system in the liver of WD.

Liver injury in HIV monoinfected patients: should we turn a blind eye to it?

With the advent of combined antiretroviral therapies, liver diseases have emerged as a key issue in the management of HIV infection. In addition to hepatitis co-infection, a large spectrum of liver diseases can affect the prognosis of HIV infection. Acute or progressive hepatic injuries require an accurate diagnosis for a better clinical management. Here, we provide an overview of the main liver diseases associated with HIV infection, which are not covered by the widely documented field of viral hepatitis co-infection.

[Lipodystrophy and echographic hepatic steatosis in HIV-positive patients under highly active antiretroviral therapy (HAART) in Yaounde (Cameroon)]

The association between sonographic liver steatosis and clinical lipodystrophy in AIDS patients treated by highly active antiretroviral therapy (HAART) has been studied. We conducted a cross-sectional study reviewing medical files of 117 AIDS patients followed up in Yaounde, Cameroon (6.3 F/1 M, mean age = 40 ± 9.4 years), and treated the patients with HAART protocol comprising stavudine or zidovudine for at least six months. All participants underwent abdominal ultrasonography and anthropometric assessment including body mass index (BMI). Data analysis included determining the association between sonographic liver steatosis, clinical lipodystrophy, and other clinical and biological data using the ¢(2) test, and the calculation of odd ratio. Fifty-one patients presented clinical lipodystrophy. The sonographic prevalence of hepatomegaly and splenomegaly was 70.1% and 25.6%, respectively. The overall prevalence of sonographic steatosis was 28.2%; specifically 37.3% among lipodystrophic patients and 21.1% among nonlipodystrophic patients (P = 0.03). According to the type of lipodystrophy, the prevalence was 40.6% among lipohypertrophic patients, 38.5% among lipodystrophic patients, and 16.7% among lipoatrophic patients. Clinical lipohypertrophy was statistically associated with a higher prevalence of sonographic steatosis (odd ratio = 2.5; 95% CI: [1.01-6.39], and P = 0.04). HAART protocol including stavudine was associated with lipodystrophy. The prevalence of sonographic liver steatosis is high among AIDS patients under HAART and is associated with lipohypertrophy.

Human immunodeficiency virus infection and the liver

Liver disease in human immunodeficiency virus (HIV)-infected individuals encompasses the spectrum from abnormal liver function tests, liver decompensation, with and without evidence of cirrhosis on biopsy, to non-alcoholic liver disease and its more severe form, non-alcoholic steatohepatitis and hepatocellular cancer. HIV can infect multiple cells in the liver, leading to enhanced intrahepatic apoptosis, activation and fibrosis. HIV can also alter gastro-intestinal tract permeability, leading to increased levels of circulating lipopolysaccharide that may have an impact on liver function. This review focuses on recent changes in the epidemiology, pathogenesis and clinical presentation of liver disease in HIV-infected patients, in the absence of co-infection with hepatitis B virus or hepatitis C virus, with a specific focus on issues relevant to low and middle income countries.